Conventionally, a tube-like catheter is inserted into a tubular organ such as the blood vessel, the ureter, the bile duct, or the trachea, and a contrast agent or a medical solution such as an anticancer agent or a nutrient is injected through the catheter. In the case where a lesion part such as cancer cells is produced in the liver, for example, a tip end portion of a catheter is indwelled in the hepatic artery which is in front of the lesion part, and a medical solution such as an anticancer agent is administered. In a tubular organ such as the hepatic artery, however, it is usual that the organ has a thick main tube, and a thin branch tube which branches off the main tube, and a case sometimes occurs where a catheter cannot be introduced into the thin branch tube.
In such a case, for example, a balloon catheter may be used which has: the tube-like body; an inflatable balloon which is placed on the outer circumference of a tip end portion of the body; and a side hole which is disposed on the side of the base end with respect to the place where the balloon is placed on the body. The balloon catheter is configured so that, by using a guide wire or the like, the tip end portion is placed in a portion of the main tube which is slightly beyond the portion where the branch tube branches off, the balloon is then inflated to close the main tube, a plug-like stopper is then inserted from the base end opening of the body to close the tip end opening of the body, a medical solution is injected from the base end side of the body in this state, to flow out from the side hole, and the medical solution is administered to the lesion part produced in the branch tube. In the case of such a balloon catheter, however, the plug-like stopper must be inserted into the body as described above, thereby closing the tip end opening of the body. Therefore, the work is cumbersome and troublesome, the surgical time is prolonged, and the burden on the patient is increased. Consequently, this countermeasure is not preferable.
Therefore, a balloon catheter which does not require a plug-like stopper has been proposed. For example, Patent Literature 1 below discloses an intravascular indwelling catheter having: a catheter body having a main inner cavity for injecting a medical solution, and a balloon inner cavity for inflating a balloon; a side hole which is formed in the middle of the catheter body, and which communicates with the main inner cavity; and a balloon portion which is placed in a tip end portion of the catheter body so as to communicate with the tip end opening of the balloon inner cavity. A physiological saline solution or the like is caused to flow into the balloon inner cavity to inflate the balloon portion in the tip end of the catheter body, and therefore the tip end opening of the main inner cavity is closed. When a medical solution is injected into the main inner cavity in this state the medical solution is allowed to flow out from the side hole, while preventing the the medical solution from flowing out from the tip end opening of the main inner cavity.